1. Field of the Invention
The invention relates to endoscopic medical devices. More particularly, the invention relates to an endoscopic infusion device having a needle which is movable within an outer tube from a first position to a second position.
2. State of the Art
Endoscopic infusion needle devices are used in the treatment of various digestive disorders to control bleeding or potential bleeding lesions in the esophagus, stomach, duodenum, and colon. The state of the art devices include a relatively long catheter, typically having an overall length of about 200 cm, within which an inner injection tube having a distal injection needle is slideably disposed. A proximal actuating handle is coupled to the catheter and the injection tube for moving one relative to the other. Fluid access to the injection tube is typically provided via a luer connector on the handle. In addition, a second luer connector is usually provided on the handle for introducing a saline irrigant into the annular space between the catheter and the injection tube.
Endoscopic infusion needle devices are typically delivered to an injection site through the lumen of an endoscope. In order to protect the lumen of the endoscope from damage, the handle of the infusion needle device is manipulated to withdraw the distal injection needle into the lumen of the catheter before inserting the device into the endoscope. This is important to prevent exposure of the sharp point of the injection needle as the device is moved through the lumen of the endoscope. When the distal end of the infusion needle device is located at the injection site, its handle is again manipulated to move the injection needle distally out of the lumen of the catheter. When advanced to the most distal position, the exposed portion of the injection needle should be approximately 4-6 mm in length. The injection procedure is often preceded by washing the site with saline in order to clear the field of view before piercing the injection site with the needle. The saline wash is delivered via the annular space between the catheter and the injection tube. After the injection site has been pierced, a sclerosing agent or vasoconstrictor composition is delivered through the injection tube and the needle into the injection site. The procedure may be performed at several injection sites before the injection needle device is removed from the endoscope. Between injections, however, the needle is withdrawn into the catheter to prevent inadvertent punctures or needle pricks.
The state of the art endoscopic infusion needle devices all suffer from similar design problems which are related to the movement of the needle into and out of the catheter. For example, it is difficult to assure that the injection needle will remain within the catheter when it is withdrawn, or to assure that the injection needle will not puncture the wall of the catheter during movement of the device through the endoscope. The reason for these problems is related to the dimensions of the device and the often tortuous path provided by the lumen of the endoscope. As mentioned above, the desired relative movement of the needle and the catheter is only on the order of 10 mm, whereas the overall length of the device is on the order of two hundred times that amount. Thus, the movement of the proximal ends of the catheter and the injection tube by an amount on the order of 10 mm cannot assure that the distal ends of the catheter and the injection tube will move exactly the same amount without requiring exacting tolerances. This issue is exacerbated by the tortuous path taken through the endoscope by the device. This tortuous path also causes the injection needle to be deflected relative to the axis of the catheter such that the sharp point of the needle touches the inner wall of the catheter. As the device is moved through the endoscope, it is thereby possible for the injection needle to puncture the catheter wall, rendering the device inoperative, and possibly damaging the lumen of the endoscope.